diff options
Diffstat (limited to 'util')
| -rwxr-xr-x | util/riscv/sifive-gpt.py | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/util/riscv/sifive-gpt.py b/util/riscv/sifive-gpt.py new file mode 100755 index 0000000000..cb77302528 --- /dev/null +++ b/util/riscv/sifive-gpt.py @@ -0,0 +1,181 @@ +#!/usr/bin/python3 +# This file is part of the coreboot project. +# +# Copyright (C) 2018 Jonathan Neuschäfer +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; version 2 of the License. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. + +import sys, os, struct, uuid, zlib, io + +# This script wraps the bootblock in a GPT partition, because that's what +# SiFive's bootrom will load. + + +# Size of a GPT disk block, in bytes +BLOCK_SIZE = 512 +BLOCK_MASK = BLOCK_SIZE - 1 + +# Size of the bootcode part of the MBR +MBR_BOOTCODE_SIZE = 0x1be + +# A protecive MBR, without the bootcode part +PROTECTIVE_MBR_FOOTER = bytes([ + 0x00, 0x00, 0x02, 0x00, 0xee, 0xff, 0xff, 0xff, + 0x01, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x55, 0xaa +]) + + +# A "protective MBR"[1], which may also contain some boot code. +# [1]: https://en.wikipedia.org/wiki/GUID_Partition_Table#PROTECTIVE-MBR +class ProtectiveMBR: + def __init__(self): + self.bootcode = bytes(MBR_BOOTCODE_SIZE) + + def generate(self, stream): + assert len(self.bootcode) == MBR_BOOTCODE_SIZE + mbr = self.bootcode + PROTECTIVE_MBR_FOOTER + assert len(mbr) == BLOCK_SIZE + stream.write(mbr) + + +# Generate a GUID from a string +class GUID(uuid.UUID): + def __init__(self, string): + super().__init__(string) + + def get_bytes(self): + return self.bytes_le + +DUMMY_GUID_DISK_UNIQUE = GUID('17145242-abaa-441d-916a-3f26c970aba2') +DUMMY_GUID_PART_UNIQUE = GUID('7552133d-c8de-4a20-924c-0e85f5ea81f2') +GUID_TYPE_FSBL = GUID('5B193300-FC78-40CD-8002-E86C45580B47') + + +# A GPT disk header +# https://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_table_header_(LBA_1) +class GPTHeader: + def __init__(self): + self.current_lba = 1 + self.backup_lba = 1 + self.first_usable_lba = 2 + self.last_usable_lba = 0xff # dummy value + self.uniq = DUMMY_GUID_DISK_UNIQUE + self.part_entries_lba = 2 + self.part_entries_number = 0 + self.part_entries_crc32 = 0 + self.part_entry_size = 128 + + def pack_with_crc(self, crc): + header_size = 92 + header = struct.pack('<8sIIIIQQQQ16sQIII', + b'EFI PART', 0x100, header_size, crc, 0, + self.current_lba, self.backup_lba, self.first_usable_lba, + self.last_usable_lba, self.uniq.get_bytes(), + self.part_entries_lba, self.part_entries_number, + self.part_entry_size, self.part_entries_crc32) + assert len(header) == header_size + return header + + def generate(self, stream): + crc = zlib.crc32(self.pack_with_crc(0)) + header = self.pack_with_crc(crc) + stream.write(header.ljust(BLOCK_SIZE, b'\0')) + + +# A GPT partition entry. +# https://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_entries_(LBA_2-33) +class GPTPartition: + def __init__(self): + self.type = GUID('00000000-0000-0000-0000-000000000000') + self.uniq = GUID('00000000-0000-0000-0000-000000000000') + self.first_lba = 0 + self.last_lba = 0 + self.attr = 0 + self.name = '' + + def generate(self, stream): + name_utf16 = self.name.encode('UTF-16LE') + part = struct.pack('<16s16sQQQ72s', + self.type.get_bytes(), self.uniq.get_bytes(), + self.first_lba, self.last_lba, self.attr, + name_utf16.ljust(72, b'\0')) + assert len(part) == 128 + stream.write(part) + + +class GPTImage: + # The final image consists of: + # - A protective MBR + # - A GPT header + # - A few GPT partition entries + # - The content of the bootblock + def __init__(self): + self.mbr = ProtectiveMBR() + self.header = GPTHeader() + self.partitions = [ GPTPartition() for i in range(8) ] + self.bootblock = b'' + + + # Fix up a few numbers to ensure consistency between the different + # components. + def fixup(self): + # Align the bootblock to a whole number to LBA blocks + bootblock_size = (len(self.bootblock) + BLOCK_SIZE - 1) & ~BLOCK_MASK + self.bootblock = self.bootblock.ljust(bootblock_size) + + # Propagate the number of partition entries + self.header.part_entries_number = len(self.partitions) + self.header.first_usable_lba = 2 + self.header.part_entries_number // 4 + + # Create a partition entry for the bootblock + self.partitions[0].type = GUID_TYPE_FSBL + self.partitions[0].uniq = DUMMY_GUID_PART_UNIQUE + self.partitions[0].first_lba = self.header.first_usable_lba + self.partitions[0].last_lba = \ + self.header.first_usable_lba + bootblock_size // BLOCK_SIZE + + # Calculate the CRC32 checksum of the partitions array + partition_array = io.BytesIO() + for part in self.partitions: + part.generate(partition_array) + self.header.part_entries_crc32 = zlib.crc32(partition_array.getvalue()) + + + def generate(self, stream): + self.mbr.generate(stream) + self.header.generate(stream) + for part in self.partitions: + part.generate(stream) + stream.write(self.bootblock) + + +if __name__ == '__main__': + if len(sys.argv) != 3: + print('Usage:', file=sys.stderr) + print(' %s bootblock.raw.bin bootblock.bin' % sys.argv[0], + file=sys.stderr) + sys.exit(1) + + image = GPTImage() + + with open(sys.argv[1], 'rb') as f: + image.bootblock = f.read() + + image.fixup() + + with open(sys.argv[2], 'wb') as f: + image.generate(f) |